This invention relates to methods, compositions and devices for the carbonation of aqueous beverages at the point of consumption. Carbonation is accomplished by contacting the beverage to be carbonated with "molecular sieves", i.e., crystalline aluminosilicates, which contain absorbed gaseous carbon dioxide. Carbon dioxide is released from such molecular sieves by displacement with water from the beverage solution. The liberated carbon dioxide is then dissolved by the liquid to form the carbonated beverage.
Commercial beverage carbonation usually involves carbon dioxide-liquid contact under pressure with intensive mixing in a cooled container. Such commercial methods, of course, require elaborate and sophisticated equipment not available in the home or at the point of beverage consumption.
Several simple carbonation techniques which are suitable for home use have been disclosed in the art. Most commonly, such prior art carbonation systems utilize a chemical "couple" to generate carbon dioxide in situ within the beverage to be carbonated. Such a couple usually consists of the combination of an inorganic carbonate such as sodium bicarbonate and an edible food acid such as citric acid or an acid-acting ionic exchange resin. Contact between compounds of this type in aqueous solutions results in the formation of gaseous carbon dioxide and a salt of the food acid. Several patents (Mitchell et a., U.S. Pat. No. 3,241,977, Mar. 22, 1966; Mitchell et al., U.S. Pat. No. 3,467,526, Sept. 16, 1969; Hovey, U.S. Pat. No. 3,492,671, Jan. 27, 1970; and Hughes, U.S. Pat. No. 2,742,363, Apr. 17, 1956) describe preferred embodiments of such acid-bicarbonate or acid resin-bicarbonate systems in detail. All of these methods, however, result in formation of undesirable off-tasting organic salts in solution or require utilization of complex ion exchange material to prevent these salts from dissolving in the beverage. Such salts are particularly noticeable and objectionable to the consumer when formed in substantial amounts in achieving relatively high levels of carbonation.
Another home carbonation technique utilizes dry beverage compositions containing water-reactive carbonic acid anhydrides which release CO.sub.2 or H.sub.2 CO.sub.3 in aqueous solution. (Feldman et al., U.S. pat. No. 3,441,417, Apr. 29, 1969) These compositions, however, require rather complex formulation and, in many instances, require incorporation of a buffering system into the beverage solution.
Accordingly, it is an object of the present invention to provide a simple method for beverge carbonation which can be employed in the home or at the point of consumption. It is a further object of the instant invention to provide such a simple carbonation method which does not result in undesirble build-up of off-tasting organic salts in solution. It is a further object of the present invention to provide such a beverage carbonation method which does not necessitate formulation of complex dry carbonation compositions. It is a further object of the instant invention to provide simple but effective devices for point-of-consumption beverage carbonation.
It has now been discovered that by employing readily available molecular sieves which contain adsorbed carbon dioxide and which readily release such carbon dioxide upon contact with water, the above-described objectives can be accomplished.